The report follows Friday’s devastating 8.9-magnitude earthquake and tsunami in the area, with a commission official suggesting that even if there was a meltdown it would not affect humans beyond a six-mile radius.

Parts of the reactor’s nuclear fuel rods were briefly exposed to the air after cooling water levels dropped through evaporation, and a fire engine was pumping water into the reactor, Jiji news agency reported.

The rods, which create heat through a nuclear reaction, can release radioactivity when exposed to the air. Without water the rods cannot be cooled properly, Fox News reported.

The water levels are recovering, operator Tokyo Electric Power Company (TEPCO), told Jiji. In addition a TEPCO spokesman told AFP that “we believe the reactor is not melting down or cracking. We are trying to raise the water level.”

But moments later Kyodo News reported that radioactive caesium had been detected near the Fukushima plant, citing information from the nuclear safety agency.

Earlier Saturday, the Japanese government declared an atomic emergency amid growing international concern over its reactors.

As an industrial powerhouse nation poor in energy resources, Japan draws about 30 percent of its total power from its 53 nuclear plants.

About 45,000 people who live within a six-mile radius of the No. 1 plant were earlier told to evacuate — raising the number from the fewer than 6,000 people within two miles told to leave Friday.